Marine Microalgae Adsorption Of Heavy Metals And Their Interaction Research

With the rapid development of the world economy,heavy metal pollution problems loom large day by day.Heavy metal pollution not only caused great loss of international economy,but also endanger people's life security,so heavy metal pollution treatment has got extensive attention.At the same time,fossil energy shortage problem is also imminent,such as demand for oil grows rapidly and its prices continue to rise,so fossil energy shortage prompted make people pay more and more attention to the development of new energy.Marine microalgae has a high adsorption performance,the use of whose adsorption of heavy metal ions is a new biological adsorption method.At the same time,being based on the unique biological characteristics of marine microalgae cells,it is also considered as one of the most promising biological resources to replace fossil fuels,which has good development prospect in the preparation of biofuels.Combining with the current research hotspot,in this study,marine microalgae was utilized to adsorb heavy metal in water and the variation between growth,lipid accumulation and the adsorbing capacity of heavy metals were determined under heavy metals stress.Firstly,a marine microalgae with high lipid content was screened out by the modified Nile red fluorescence and identified as Nannochloropsis oceanica strain CS-179 by 18 SrRNA sequence.Secondly,Zn2+,Cd2+,Pb2+and Cu2+which are strict restricted from aqueous solution were used to study the adsorption by Nannochloropsis oceanica and their effect on growth status,lipid content of Nannochloropsis oceanica.In this paper,optical density value was used to reflect the effects of different concentrations of heavy metal ions on the growth of Nannochloropsis oceanica.The modified Nile red staining method was used to stain the lipid in the algae cells.The changes of lipid content of Nannochloropsis oceanica under different concentrations of Zn2+,Cd2+,Pb2+and Cu2+were studied according to the change of fluorescence value.TPPS can be derived with heavy metals into TPPS-heavy metal complex under specific conditions,the adsorbing capacity of heavy metals was detected by high performance liquid chromatography.In0,2,4,6,8 days of different concentrations of heavy metals Zn2+,Cd2+,Pb2+and Cu2+under the stress of Nannochloropsis oceanica were detected,the growth status was determined by ELIASA,the lipid content was determined by the modified Nile red fluorescence,and the adsorbing capacity of heavy metals was determined by HPLC.The experimental results showed that the growth status of Nannochloropsis oceanica was related to the concentration of Zn2+,Cd2+,Pb2+and Cu2+,and the growth of Nannochloropsis oceanica was inhibited under the concentration of 8mg/L of Zn2+,1mg/L of Cd2+,80mg/L of Pb2+ and 2mg/L of Cu2+.The influence degree was Cd2+>Cu2+>Zn2+>Pb2+.The lipid accumulation ability and adsorption capacity of Nannochloropsis oceanica were high under a certain concentration range of Zn2+,Cd2+,Pb2+and Cu2+.Zn2+,Cd2+,Pb2+and Cu2+ can promote lipid accumulation of Nannochloropsis oceanica,one of which Cd2+ promotes the most significant effect.Heavy metal ions can promote the lipid accumulation of Nannochloropsis oceanica may be due to hormesis.Nannochloropsis oceanica has the adsorption ability of Zn2+,Cd2+,Pb2+and Cu2+ ions under different concentrations,and the adsorption characteristics were different.The adsorption rate of Zn2+,Cd2+,Pb2+,Cu2+ were 69%,16%,70%,and 85%,respectively.Integrate the performance of growth status,lipid accumulationand heavy metal adsorption,the optimum order of four kinds of heavy metal ions for Nannochloropsis oceanica is Pb2+>Zn2+>Cu2+>Cd2+.Once more,the adsorption process was studied,and the sorption mechanism conformed to the Pseudo-second-order equation and Freundlich model.Nannochloropsis oceanica can be not only used for the adsorption of heavy metals,but also used as biofuel raw material preparation.On the one hand,it is expected to alleviate the problem of fossil energy shortage in China,this methods is green and environmental;on the other hand,it can also accumulate heavy metals,which is conducive to environmental pollution control and avoid secondary pollution problems.It is of great significance for the environmental pollution control and the development of clean energy.This experiment has a certain reference value for heavy metal adsorption and biodiesel exploitation of microalgae.